The present invention relates to storing information. More specifically, the present invention relates to a magnetic storage.
In a conventional magnetic disk storage, information is stored in a continuous magnetic thin film that is over a rigid nonmagnetic disk. Each bit of information is stored by magnetizing a small area on the thin magnetic film using a write head that will provide a suitable magnetic field. The magnetic moment, the area and the location of that small area present a bit of binary information, and they must be defined precisely to allow a magnetic sensor, called a read head, to retrieve the written information.
The conventional magnetic disk storage suffers several drawbacks that hinder realization of ultrahigh density storage. First, the magnetic moments of a continuous film have an infinite number of possibilities. Therefore, the write head must write very precisely in defining the magnetic moment, the location, and the area of each bit on the magnetic thin film. A slight error in doing so will not only create the error in the bit, but also could miswrite the neighboring bits, causing errors in reading. Second, a continuous film is very good in linking exchange interaction and magnetostatic interaction that are between the bits. When the bits are very close, writing of one bit could lead to writing of its neighbors because of the exchange interaction and magnetostatic interaction between the bits. Thirdly, the continuous magnetic film makes many bits have no physical boundaries between them, making the reading and writing in a blind fashion. This means that the location of each bit is found by calculating the movements of the disk and the write or read heads, instead of physically sensing the actual bit location. Fourth, the continuous magnetic film also makes the boundary of two bits with different magnetization ragged, creating noise in reading.
As demand for more information continues to grow, the need for high density data storage will keep increasing. To achieve ultrahigh density magnetic storage, the drawbacks of the conventional magnetic storage mentioned above must be overcome.